Compatibility of AMD Radeon ProRender
TL;DR: Yes, you can use the AMD Radeon Pro 5300M for GPU rendering with the AMD Radeon™ ProRender, if you're using macOS 10.13.3 or later.

There are two relevant requirements:

The minimum requirements for running Blender
The minimum requirements for AMD Radeon™ ProRender for Blender


Minimum requirements for running Blender (2020-08-07)
You will need macOS 10.12 or later for starting Blender 2.8x and macOS 10.13 or later for Blender 2.90. Additionally a GPU is needed that is GCN first generation or later, which is the case for your GPU from the Radeon Pro 5000M series.

Minimum requirements for AMD Radeon™ ProRender for Blender (2020-08-07)
According to AMDs website the following requirements have to be met:

Blender® 2.80, 2.81, 2.82, and 2.83 (experimental builds not supported) for Microsoft Windows®, macOS®, and Linux®


macOS® High Sierra 10.13.3 and up (10.13.4 required for external GPU support)


Runs on both GPUs and CPUs. OpenCL™ 1.2 support required for GPUs on Windows® and Linux®. Metal® 2 support required for GPUs on macOS®



Compatible Apple® Mac® Hardware:

MacBook® (Early 2015 or newer), MacBook Pro® (Mid 2012 or newer), MacBook Air® (Mid 2012 or newer), Mac mini® (Late 2012 or newer), iMac® (Late 2012 or newer), iMac Pro™ (Late 2017 or newer), Mac Pro® (Late 2013 or newer) (Models without discrete AMD Radeon™, Radeon™ Pro, or AMD FirePro™ graphics will be limited to CPU rendering with Radeon™ ProRender)




In summary, if you fulfill the following requirements, you're able to GPU render with the AMD Radeon™ ProRender:

MacBook Pro is from mid 2012 or later
Operating system is macOS 10.13.3 or later
Blender version is 2.80 or later, but not 2.9x yet